//========================================================================
// GLFW 3.3 OSMesa - www.glfw.org
//------------------------------------------------------------------------
// Copyright (c) 2016 Google Inc.
// Copyright (c) 2016-2017 Camilla Löwy <elmindreda@glfw.org>
//
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented; you must not
//    claim that you wrote the original software. If you use this software
//    in a product, an acknowledgment in the product documentation would
//    be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such, and must not
//    be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source
//    distribution.
//
//========================================================================
// Please use C89 style variable declarations in this file because VS 2010
//========================================================================

#include <stdlib.h>
#include <string.h>
#include <assert.h>

#include "internal.h"

static void makeContextCurrentOSMesa(_GLFWwindow* window) {
  if (window) {
    int width, height;
    _glfwPlatformGetFramebufferSize(window, &width, &height);

    // Check to see if we need to allocate a new buffer
    if ((window->context.osmesa.buffer == NULL) ||
        (width != window->context.osmesa.width) ||
        (height != window->context.osmesa.height)) {
      free(window->context.osmesa.buffer);

      // Allocate the new buffer (width * height * 8-bit RGBA)
      window->context.osmesa.buffer = calloc(4, (size_t)width * height);
      window->context.osmesa.width = width;
      window->context.osmesa.height = height;
    }

    if (!OSMesaMakeCurrent(window->context.osmesa.handle,
                           window->context.osmesa.buffer,
                           GL_UNSIGNED_BYTE,
                           width,
                           height)) {
      _glfwInputError(GLFW_PLATFORM_ERROR,
                      "OSMesa: Failed to make context current");
      return;
    }
  }

  _glfwPlatformSetTls(&_glfw.contextSlot, window);
}

static GLFWglproc getProcAddressOSMesa(const char* procname) {
  return (GLFWglproc)OSMesaGetProcAddress(procname);
}

static void destroyContextOSMesa(_GLFWwindow* window) {
  if (window->context.osmesa.handle) {
    OSMesaDestroyContext(window->context.osmesa.handle);
    window->context.osmesa.handle = NULL;
  }

  if (window->context.osmesa.buffer) {
    free(window->context.osmesa.buffer);
    window->context.osmesa.width = 0;
    window->context.osmesa.height = 0;
  }
}

static void swapBuffersOSMesa(_GLFWwindow* window) {
  // No double buffering on OSMesa
}

static void swapIntervalOSMesa(int interval) {
  // No swap interval on OSMesa
}

static int extensionSupportedOSMesa(const char* extension) {
  // OSMesa does not have extensions
  return GLFW_FALSE;
}

//////////////////////////////////////////////////////////////////////////
//////                       GLFW internal API                      //////
//////////////////////////////////////////////////////////////////////////

GLFWbool _glfwInitOSMesa(void) {
  int i;
  const char* sonames[] =
  {
#if defined(_GLFW_OSMESA_LIBRARY)
    _GLFW_OSMESA_LIBRARY,
#elif defined(_WIN32)
    "libOSMesa.dll",
    "OSMesa.dll",
#elif defined(__APPLE__)
    "libOSMesa.8.dylib",
#elif defined(__CYGWIN__)
    "libOSMesa-8.so",
#else
    "libOSMesa.so.8",
    "libOSMesa.so.6",
#endif
    NULL
  };

  if (_glfw.osmesa.handle)
    return GLFW_TRUE;

  for (i = 0; sonames[i]; i++) {
    _glfw.osmesa.handle = _glfw_dlopen(sonames[i]);
    if (_glfw.osmesa.handle)
      break;
  }

  if (!_glfw.osmesa.handle) {
    _glfwInputError(GLFW_API_UNAVAILABLE, "OSMesa: Library not found");
    return GLFW_FALSE;
  }

  _glfw.osmesa.CreateContextExt = (PFN_OSMesaCreateContextExt)
      _glfw_dlsym(_glfw.osmesa.handle, "OSMesaCreateContextExt");
  _glfw.osmesa.CreateContextAttribs = (PFN_OSMesaCreateContextAttribs)
      _glfw_dlsym(_glfw.osmesa.handle, "OSMesaCreateContextAttribs");
  _glfw.osmesa.DestroyContext = (PFN_OSMesaDestroyContext)
      _glfw_dlsym(_glfw.osmesa.handle, "OSMesaDestroyContext");
  _glfw.osmesa.MakeCurrent = (PFN_OSMesaMakeCurrent)
      _glfw_dlsym(_glfw.osmesa.handle, "OSMesaMakeCurrent");
  _glfw.osmesa.GetColorBuffer = (PFN_OSMesaGetColorBuffer)
      _glfw_dlsym(_glfw.osmesa.handle, "OSMesaGetColorBuffer");
  _glfw.osmesa.GetDepthBuffer = (PFN_OSMesaGetDepthBuffer)
      _glfw_dlsym(_glfw.osmesa.handle, "OSMesaGetDepthBuffer");
  _glfw.osmesa.GetProcAddress = (PFN_OSMesaGetProcAddress)
      _glfw_dlsym(_glfw.osmesa.handle, "OSMesaGetProcAddress");

  if (!_glfw.osmesa.CreateContextExt ||
      !_glfw.osmesa.DestroyContext ||
      !_glfw.osmesa.MakeCurrent ||
      !_glfw.osmesa.GetColorBuffer ||
      !_glfw.osmesa.GetDepthBuffer ||
      !_glfw.osmesa.GetProcAddress) {
    _glfwInputError(GLFW_PLATFORM_ERROR,
                    "OSMesa: Failed to load required entry points");

    _glfwTerminateOSMesa();
    return GLFW_FALSE;
  }

  return GLFW_TRUE;
}

void _glfwTerminateOSMesa(void) {
  if (_glfw.osmesa.handle) {
    _glfw_dlclose(_glfw.osmesa.handle);
    _glfw.osmesa.handle = NULL;
  }
}

#define setAttrib(a, v) \
  { \
    assert(((size_t)index + 1) < sizeof(attribs) / sizeof(attribs[0])); \
    attribs[index++] = a; \
    attribs[index++] = v; \
  }

GLFWbool _glfwCreateContextOSMesa(_GLFWwindow* window,
                                  const _GLFWctxconfig* ctxconfig,
                                  const _GLFWfbconfig* fbconfig) {
  OSMesaContext share = NULL;
  const int accumBits = fbconfig->accumRedBits +
                        fbconfig->accumGreenBits +
                        fbconfig->accumBlueBits +
                        fbconfig->accumAlphaBits;

  if (ctxconfig->client == GLFW_OPENGL_ES_API) {
    _glfwInputError(GLFW_API_UNAVAILABLE,
                    "OSMesa: OpenGL ES is not available on OSMesa");
    return GLFW_FALSE;
  }

  if (ctxconfig->share)
    share = ctxconfig->share->context.osmesa.handle;

  if (OSMesaCreateContextAttribs) {
    int index = 0, attribs[40];

    setAttrib(OSMESA_FORMAT, OSMESA_RGBA);
    setAttrib(OSMESA_DEPTH_BITS, fbconfig->depthBits);
    setAttrib(OSMESA_STENCIL_BITS, fbconfig->stencilBits);
    setAttrib(OSMESA_ACCUM_BITS, accumBits);

    if (ctxconfig->profile == GLFW_OPENGL_CORE_PROFILE) {
      setAttrib(OSMESA_PROFILE, OSMESA_CORE_PROFILE);
    } else if (ctxconfig->profile == GLFW_OPENGL_COMPAT_PROFILE) {
      setAttrib(OSMESA_PROFILE, OSMESA_COMPAT_PROFILE);
    }

    if (ctxconfig->major != 1 || ctxconfig->minor != 0) {
      setAttrib(OSMESA_CONTEXT_MAJOR_VERSION, ctxconfig->major);
      setAttrib(OSMESA_CONTEXT_MINOR_VERSION, ctxconfig->minor);
    }

    if (ctxconfig->forward) {
      _glfwInputError(GLFW_VERSION_UNAVAILABLE,
                      "OSMesa: Forward-compatible contexts not supported");
      return GLFW_FALSE;
    }

    setAttrib(0, 0);

    window->context.osmesa.handle =
        OSMesaCreateContextAttribs(attribs, share);
  } else {
    if (ctxconfig->profile) {
      _glfwInputError(GLFW_VERSION_UNAVAILABLE,
                      "OSMesa: OpenGL profiles unavailable");
      return GLFW_FALSE;
    }

    window->context.osmesa.handle =
        OSMesaCreateContextExt(OSMESA_RGBA,
                               fbconfig->depthBits,
                               fbconfig->stencilBits,
                               accumBits,
                               share);
  }

  if (window->context.osmesa.handle == NULL) {
    _glfwInputError(GLFW_VERSION_UNAVAILABLE,
                    "OSMesa: Failed to create context");
    return GLFW_FALSE;
  }

  window->context.makeCurrent = makeContextCurrentOSMesa;
  window->context.swapBuffers = swapBuffersOSMesa;
  window->context.swapInterval = swapIntervalOSMesa;
  window->context.extensionSupported = extensionSupportedOSMesa;
  window->context.getProcAddress = getProcAddressOSMesa;
  window->context.destroy = destroyContextOSMesa;

  return GLFW_TRUE;
}

#undef setAttrib

//////////////////////////////////////////////////////////////////////////
//////                        GLFW native API                       //////
//////////////////////////////////////////////////////////////////////////

GLFWAPI int glfwGetOSMesaColorBuffer(GLFWwindow* handle, int* width,
                                     int* height, int* format, void** buffer) {
  void* mesaBuffer;
  GLint mesaWidth, mesaHeight, mesaFormat;
  _GLFWwindow* window = (_GLFWwindow*)handle;
  assert(window != NULL);

  _GLFW_REQUIRE_INIT_OR_RETURN(GLFW_FALSE);

  if (!OSMesaGetColorBuffer(window->context.osmesa.handle,
                            &mesaWidth,
                            &mesaHeight,
                            &mesaFormat,
                            &mesaBuffer)) {
    _glfwInputError(GLFW_PLATFORM_ERROR,
                    "OSMesa: Failed to retrieve color buffer");
    return GLFW_FALSE;
  }

  if (width)
    *width = mesaWidth;
  if (height)
    *height = mesaHeight;
  if (format)
    *format = mesaFormat;
  if (buffer)
    *buffer = mesaBuffer;

  return GLFW_TRUE;
}

GLFWAPI int glfwGetOSMesaDepthBuffer(GLFWwindow* handle,
                                     int* width, int* height,
                                     int* bytesPerValue,
                                     void** buffer) {
  void* mesaBuffer;
  GLint mesaWidth, mesaHeight, mesaBytes;
  _GLFWwindow* window = (_GLFWwindow*)handle;
  assert(window != NULL);

  _GLFW_REQUIRE_INIT_OR_RETURN(GLFW_FALSE);

  if (!OSMesaGetDepthBuffer(window->context.osmesa.handle,
                            &mesaWidth,
                            &mesaHeight,
                            &mesaBytes,
                            &mesaBuffer)) {
    _glfwInputError(GLFW_PLATFORM_ERROR,
                    "OSMesa: Failed to retrieve depth buffer");
    return GLFW_FALSE;
  }

  if (width)
    *width = mesaWidth;
  if (height)
    *height = mesaHeight;
  if (bytesPerValue)
    *bytesPerValue = mesaBytes;
  if (buffer)
    *buffer = mesaBuffer;

  return GLFW_TRUE;
}

GLFWAPI OSMesaContext glfwGetOSMesaContext(GLFWwindow* handle) {
  _GLFWwindow* window = (_GLFWwindow*)handle;
  _GLFW_REQUIRE_INIT_OR_RETURN(NULL);

  if (window->context.client == GLFW_NO_API) {
    _glfwInputError(GLFW_NO_WINDOW_CONTEXT, NULL);
    return NULL;
  }

  return window->context.osmesa.handle;
}
